Radiological safety during maintenance of the primary heat transfer system of the ITER plant

The primary heat transfer system (PHTS) of the ITER plant is devoted to the heat removal from different plasma facing components: the first wall, the blanket, the divertor and the vacuum vessel. The system requires a scheduled or regular maintenance that involve component checking and changing, and a special maintenance that has a non periodic nature. During the maintenance operations some shielding barrier has to be partly or completely removed and workers are likely to be exposed to an unusual radiological dose. In the present work the occupational radiation exposure (ORE) for the maintenance activities performed at the PHTS has been assessed. The problem of the activated corrosion product (ACP) transport assessment inside the coolant has been faced and solved with the computer code PACTOLE. The working procedure protocols have been taken from the fission PWR plant experience. The shielding effectiveness of the PHTS components has been evaluated with a well tested computer code. The final result presented in the work is the collective dose for regular and special maintenance at the ITER PHTS, compared with typical data coming from the PWR operational experience